1. Overview

First and foremost, safety is paramount in any scientific endeavor. Before entering the lab, we ensure that we are properly attired with a lab coat, gloves, and safety goggles. Adhering to the principle of "safety first".The organisms used in our experiments are E. coli (engineered & control). DNA-based experiments and cell cultures constitute the majority of our lab work. These organisms fall under the category of Biosafety Level 2. We conducted our experiments in the labs of Nanjing University School of Life Sciences, where many instructors and lab technicians guided us on safety precautions. Before starting the experiments, all wet lab members underwent two online training sessions and one in-lab workshop on safety procedures, which were led by lab technicians. The safety procedures provided invaluable throughout the duration of our experiments.

2. Special requirements for personal protection

First, when utilizing dyes that target DNA or protein in electrophoresis, at least two layers of gloves are required. DO NOT allow dye to contact skin directly. Dispose of the outer glove immediately after working with dyes. Secondly, when using UV light sources, cover all exposed skin in the area of effect, use proper eye protection at all times. Do not work under or sit in front of the laminar flow hood when the UV light is on.

3. Potentially dangerous chemicals

1. TEMED is a volatile neurotoxin used as a curing agent for polyacrylamide gels. Always use TEMED under a running chemical fume hood with proper PPE and a respirator if working with large amounts. Always seal the TEMED container immediately after use in the chemical.
2. Anhydrous Acetic Acid is a highly volatile organic acid used in washing of Coomasie blue dye. Acetic acid and its fumes are highly irritating to eyes, lungs, and skin. Use proper PPE and work under a chemical fume hood when working with acetic acid. If acetic acid comes into contact with skin, wash with running water until acid is removed. If acetic acid comes into contact with eyes, wash continuously with running water at an eye wash station for more than 15 minutes, and seek medical attention immediately. Acetic acid and its fumes are highly flammable. Do not work with acetic acid in the presence of an open flame.
3. Ethanol, methanol and isopropanol are highly flammable and volatile liquids. Do not store these reagents in proximity to an open flame. Do not work with these reagents in the presence of an open flame.
4. Dangerous chemicals are stored in the designated metal Dangerous Chemicals Closet. Retrieval, use and return of chemicals from the closet should be documented clearly. All chemicals should be returned to the closet, and the closet should be locked. Do not open the closet in the presence of an open flame. Do not allow access to the closet to non-authorized personnel. Do not remove chemicals from the closet without permission. Do not unnecessarily remove chemicals from the closet. The Dangerous Chemicals Closet contains extremely dangerous acids and toxic compounds. Concentrated Hydrochloric acid, concentrated phosphoric acid, and concentrated ammonium hydroxide can cause severe damage. Trichloromethane is highly volatile and toxic.

4. Laboratory Equipment Safety

During electrophoresis, avoid touching the buffer solution as it may cause electric shocks. Exercise caution when using the centrifuge to balance the load weight. Do not leave the centrifuge running unattended. Turn off the heating instrument in time after use, and prohibit high temperature overnight operation.

Finally, the project involved the modification of gene enhance the catalytic activity and the expression of TdTs. This experiment required meticulous attention to safety protocols, particularly in the handling and disposal of genetically modified materials. Every time we finished the lab work , we would put the biological waste into the autoclave machine in order to ensure that the